US: Sound barrier key to salad safety

It is has long been the wish of the salad industry to find a way to ensure perfect sanitisation of related produce. Since 2006, and a particularly virulent E.coli outbreak the hunt has been on for methods by which food safety standards can be improved.

The outbreak did, after all, cost the fresh salads industry and eye watering $350 million in lost sales and product recalls.

Since then heralded advances have always focused on the use of chlorine washes or testing technology, which leaves the organic sector with little recourse to food safety actions.

As a result of this Earthbound Farm teamed up with the Institute for Food Safety and Health (IFSH) at the Illinois Institute of Technology to look for solutions outside the bag. One of the promising directions of research uncovered so far is a little surprising - high power ultrasound.

When applied to a leafy surface, high powered ultrasound creates millions of tiny bubbles. As they burst at a rate of a thousand times a second, they provide high-energy shock waves that can get into the leaf's nooks and crannies to dislodge pathogens, which are then whisked away in a sanitized wash. Earthbound is looking into citrus peracetic acid–based sanitizers, both of which are authorised for use with organically produced foods.

"Mostly we're after E. coli O157:H7; norovirus that causes winter vomiting, and we'll continue working with salmonella and Listeria as well," says IFSH director, Robert Brackett.

Will Daniels, senior vice president of operations and organic integrity at Earthbound, says the plan is to get the equipment out of the laboratory soon and apply it to their commercial processes as soon as possible, provided everything goes as hoped. "That's assuming the pilot studies between now and then are successful and we don't end up with pureed lettuce at the end of the line. That would be a deal breaker," Daniels adds.

Actually this is not the first time high powered ultrasound has been used for sanitisation purposes - the wine industry set the precedent by using the technology to clean barrels.

The early results look very promising and Earthbound have said that if the results are as expected then the technology will be made available to all producers, not kept exclusively.